SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fe2375afaab1c225a143f0870e0a1715519b58c7c78fd1602f6474afcf582c7' 
  AND token = 'hQyn1OVeVjJ3vXpZf7vOzafrWL++rng9JhiGwjH7Fbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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