SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e49deddb6a3f0611fbd48433409b719bcb32fcaaa3c80098632a2745bd4ee0f' 
  AND token = 'Yf4ngQ8eH1DBJHLdQ6GR9x/TIcuUzlrwxeSlS9Duxjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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