SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a16d0ef0f2932be888264c12c08f6bb9037ea44d9b876b2405fbe5caf3c71fd' 
  AND token = '+bZvlwgk+qqXOWSiUmQGDXczj7RgK1Yrs8kp2xtLz8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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