SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b564bc0bbbcda6c762c3662b1a4a8531cdd9790eee59b4085205fcb1bd849688' 
  AND token = 'pliyFs+XFUpgBhbu/Oot3X0cPfFKWc6e28+d6iCH9Qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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