SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f139a78a26db4faed31d2ef461257b29b9ecd9133851a366005fe5ff21e9cd32' 
  AND token = '0t3lrtkbw/ln+03JN7eYBNOpzGHdBWpvFsFP07U5wKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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