SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '16e51775a4ce04ecc8be2ea8719f0c6a0462762d70108f7cd82adf030534599d' 
  AND token = 'MnfHPVPU9eBm/FQXRjamYPwJrGMGOTrcUzs6tpCKhC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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