SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a4793953183a65e5b732487755cb365745fc1517d3ed91a79241fa1459b4f34' 
  AND token = 'sQtlKrE6Qks0nR3xrbcL3+VzQG8HT4G3gOifPRi3RZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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