SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4222b70fa1fcf415819802c932b997b6db762bbb34f86960562d69979320541' 
  AND token = 'df6JUn+CPqOWjmGbnw1Zdvpw9EF1AENaKVMEypum9IM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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