SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c79696748fdf6d365188401959460dac76c9d7faf085435520e3cc76892c3a3b' 
  AND token = 'BdreA7KBQe7SjaNMBzQu1KdvyotrKwy6h/UUGv88tko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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