SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6813798e807da8c116041638c980a7a4bede32be5ab9f934a8d225d2c5aaf7f0' 
  AND token = 'UhkBkEmb1snbF1R6dPuircctaRIRiqa5uQH5slyu4Ls=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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