SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8b5114ed514a78767432e3d04ad4f7df50045b444e0a5d900ca49390f17813c' 
  AND token = 'a3HXZtybrAmolgM9tKbTl/rpdAl2mZkYJ5vurSDSuOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}