SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '306077a25ec68a46ab915770d476cc4864959dcbfbe15848ed9d901f65aff192' 
  AND token = 'edaqmuy8eod4gmOR6z8ANv+YIxT30CN8VDRoZrP2ctA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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