SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '646d07e6df986cd666a46e6675ee8153e377a21f784997d8d397152518087804' 
  AND token = 'kdKJeZVY5C+e12eDc1FrtSuAvRNI94Ll6pllwbQzMLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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