SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7403379cb3071fdb4032223fcc79acdf82a25e897f8c89c08041e45bd3cd2d76' 
  AND token = '6ZRka5lIp4GZkSyd/MTaarQisvEbM1Cgx6BOD+PZBlY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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