SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6f0f193328bc0bc076f5744ebae336eb7f671120a3bb43519083041e4e5b59b' 
  AND token = 'khIoJAnJyEmZSuaMMV7cVDRLkqoa+n2/cjDM7EflJKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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