SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a14af9256d832b7bedf734f654673408ed7ac5e18ca34c52ae7dcda68a270d6a' 
  AND token = 'llk4nVlWEn/b/YP6imh/Cyo5tJLfbYmytwUWbqCxdL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}