SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39d53f776c8d2c02f6b1d14fee1b136a900e6acece86e3535e5241fa2204e191' 
  AND token = 'xinoGhat/xcsKGN6eXUw+NiFgDiw/10W3f+Sywq1IYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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