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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90373b76dcb47a041b3ca5ff1dc9ba01c354c94629e852f07230d91b1d6ac91c' 
  AND token = 'Br3c76Lx6Wi2PTXc0E6KrFKo8bdsPzh8tmP7V/jsmbA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}