SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5dcd16978595a44463b3d2fd2d21761f7ad42d556b95ed97ffc5a4840669b98' 
  AND token = 'rH6WO4hJhpMHdyIBbhOrD9Rz+xnURsKFUvjvyWdA8VA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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