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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f47a520e9fe49e0c14002520a09e67807180c6512b8dbb1e4238371b3e37c499' 
  AND token = 'AS9G7DZyuqc+dTvBkI7fT2X6BQ5AuYblE9WL54RnsnQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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