SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fcc750908d095fe412dffacdcc8809cf3e2c88c5a79342e8ba5058478feb849e' 
  AND token = 'l5Dq6NgCW3yvaqsNSwgt47gQeZZfJSLUre/GJGQhxmM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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