SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '339e3ab3c8cc2d6cc5c186c0d674301ca5e8cf829f5916589679129425a545fc' 
  AND token = '+sgNvVyL83U1kRGAsoFPR8JYZsjP0ZiLNQfz/Viz9nQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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