SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83154b2fe4891ac0f4c187f5dcaa95ff670dbd3af051e8d1b12d6ee54ac3e5b3' 
  AND token = 'tLAd2BbC0mzDmx7hbbC8vOSwBhzoWkD+QHXLrbIqySA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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