SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87816326617e2425247b3808b2b6866984c5fcb23497c714fc09a9c2657aeebc' 
  AND token = 'k93udpovWZF33g84TRUhawpGoL5jd+qBZeedvskSsfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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