SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8949a4ae4321ba8301b1526d4a33fae6c5acf3d186ff3cbda2ec9241068f515' 
  AND token = 'pO8BoSV/ajE+iyXlTh300VtJ7FmYiE6bQu+ciNuMGoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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