SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5916076cfc2da10cc57819ef24c6ea4135211781e611ac1659bccd023fb5f401' 
  AND token = 'zDEa7BXKlYU+phHmhe5yziuTWGUui5nPvK2VZ3zV3lQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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