SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39e6ffa0c34144da05e9ee96580cae718fd2fca9c269ae499028b9ce7c0e0260' 
  AND token = 'YYW5NV9tAUenevz5/rRm3F1UO0BwrXemfwALR+buIhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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