SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac9a2f7488f87f8dd0524745246ca2db728993826716b965577e96cf127eb137' 
  AND token = 'vhtV+GDNjDjlL4v17AVinPevbzEpQta7IMHPzqw08zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00075

JSON explain

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