SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a856955be97dab4199ec75c3296a4a2959a659442c0951a3cd63bc2da5273f19' 
  AND token = 'd1tYHd8ITWdRzgypub6FrdAHwMAlxzQf2FoVqiw4zVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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