SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df63e7fbdecca8d5d576bec54a9a6bb32d48c7a72daedca8a4d33555a96b6754' 
  AND token = 'uBGyOUwie/oF4dzANOTkeQBq9zXfk4RjXvKxlsbjYM8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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