SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d1e828c018beedff7b59466fd64c3efdc7830dfe45905bc2489ccb6b30037de' 
  AND token = '8ZIrplOBPEKQQ6/Epx4gBD2bpGGyIyh0V6H9Y4zjJL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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