SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f764a47deac3ef3895fa2cfb88b69d44efd4744f836e51470b745dc519ee987' 
  AND token = 'ePCjeByI8pdBKhiAUIifT7twTuIj6Ms2bkkGarSwNyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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