SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51f240a37d719e65b576faf527174e16c39e01ef437131fe0bebd963a9e08cfb' 
  AND token = 'cAHlRbEJeyNaLUymVWt1dwfhmEe6mf3fKLmC0cRvjh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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