SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85381b344597f2466a97be2b595727b9ce3d31a2299aaac2ad0d656f1bb2644b' 
  AND token = 'QFk6YudWyLKqVPzp7AlQL+QhTOQFhVuuxhjg14bLnLE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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