SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '727da4694fa6466b21a7ae699e994b0daf55bf3b14b680554d06de1678f73a39' 
  AND token = 'txBqEBcFBDg+FXKlOI6hXPtmvu1XoDG13a+SHt2VY9U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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