SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ed9d982993be6139e4d4f4be4890fcf4fac11ed3f3505678eab62a124556cd7' 
  AND token = 'xcVgqPFWfm56q+YeOF8+CaoNn5trz2y90RTQHenSrdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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