SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68d7494631883b67663b3afdfa4f43a5b4d402d8c4db1061d164fef20be9e7c6' 
  AND token = 'NV4Yg9ip88JiYE/ZGO8zVcakClxhBlSuzE2Pjof1qhg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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