SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '76d47b91b7610097966e73a5476bf7800fc49d18108402737a57f99008635e8b' 
  AND token = '0AG8qEAVWKEXcHx5t9gNhIfNEIDBsaXAtsPHUS/G9TA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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