SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6039aca5174781320d0454e8e0963b0fc6470287982d67959aff86d58849f6a' 
  AND token = 'oUXArhfZR27bvlcXmleDjKQvvT8XJiwNJRxg4m5NrqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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