SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '247bc5a6a7629f38a8da837a0bcfd2fc265fab4d8f01d5b5614e9194b6e89a94' 
  AND token = '78/XdxvKirv/ntKlu4xNDkET5kUehSsedQYVFoWTF4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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