SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9c31b5c44ade82562820cecb5470c25b448065f2a8803e5a61c824d7c8bfda4' 
  AND token = 'YQ48aRN1DYJuwFhpyaFiNvHbZPhlMKcW36GVQmcYRLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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