SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '256d363d56748c0dc257ff456d725bd70aee5c994194d40b1678f74596390c1c' 
  AND token = 'Viy9qYMmHdIazLIM9e+9VNIuJ+bMsecyBa96UMcgJ3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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