SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '314012d46987bacc74cc472cc2e17dcaff016323dbd887b65ecc48a8ae9f24c0' 
  AND token = '8MHjam9+EolXzoOW3MlGeiX+whKvItYBKJfnI30LrPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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