SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc999ee94fc5cd1f28ea702536694b2d74dec88fd674e164a1f9bfc150887399' 
  AND token = 'BGTYYXv24/SrPNjcAHIV+S0oZ5twOi+Pp8tkvxN6zwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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