SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ffc8a23da475fd80959a74385a3d6803d4bd543f4ca5380c1e22638be7e2de24' 
  AND token = 'NOItisomnvbzk07xYpwECeLVZKiQUmzgP1+Dnf3uvyc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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