SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c45d6357891f5dba98647a9f247d6ae373e90f73f79a2f7f56445daed19e4511' 
  AND token = 'LPHZ4tA6f+iodjLy9yUskaQ4kdlrDhv7mmjhMqrll/8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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