SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7698e17c9a553a4ad886def748f70b0ae819d3000427542760244788ab5a41c' 
  AND token = 'lfzGZ6hTvAWKLEggsPUCFYAlqSodobgXCfnoIIqiKco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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