SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6b912b20b6743c5c1eb9b59071212aed99b0bd7251250e5ab39d1bd8135dc05' 
  AND token = 'uQaNxUYZHWEYcYdpHnQozn3QU21zVu1wDinYQUbmCcE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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