SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6eca83a55e5c742d1880552ada9ce722a1d1bec31af984e55bd6a19845f8141c' 
  AND token = '2+PKH+G/wn50BfSLipc9jUvMPMGfVdeE7IoedfvEqdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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