SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b5fb2ab4ce6dc283e976583cf28813f4298ac73b27ab588058e3ced021243f9' 
  AND token = '9Z6v6bZOVH4LjCZux4JERiDSytnAMBythvBijprvg7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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