SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ad7ce3a8a8de6f0148f6945e5b02104b067e69bfe33b5ec23f02739c2919284' 
  AND token = 'A7nfvQKjMVOTq1GXCH/gTBbXWmsAgLjZs+n9/gkwSeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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