SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28e6febdecc56363ed543a27619ab7f64a15fa6530682235a0a97c9ebd33daa8' 
  AND token = 'tNrEHYx+SiIJkSfBnGVeNlD3PRjAhBJbTXqIEK2EZEI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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