SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '292fec10a11cacfadf36bc6f2ef2ecbaf10819cde9f4c53c5b5d537005b61b6a' 
  AND token = 'MGE4IPFPQij9fMoFNx5lnxQ47GjZhj0DwetfuuOlKjQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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