SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '018303cfd7d443489014bb8281f02d06b0513664995ac4a19e93ee8fcf4d4a68' 
  AND token = '9mYZhpSHFn4PoDjswooXejxAWqj/AL7Ajuj9phIwn+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}