SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '714ca18d9a477ea6380342e134f64be67bcd08f561666a29ceca511dbf8300a2' 
  AND token = 'nYdlQyUYWANfZQ38VBJypF+I2Z8HJGkRuwgNGKK1DjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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