SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e7c63901de9da351e453ab36317afdd846b9de7296f84d2b6135578ce4a2e74' 
  AND token = 'DMIm+Epw3IIQBzJAqE7UtmRghjYAUlT4XGsbUF7Jk/g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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