SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '74da7f65d84c288dd8076b3684eca8f82120a8b3253e6d59117b7e64b37dd0ae' 
  AND token = '1qMfJzjNqY7GBbyUQ14YHoh+duCo7MHVwhc2CGiRFLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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