SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b4a82f4e3bc23cccd9db2c9946ece7638a5546325cd4ca75261bd43850ca803' 
  AND token = 'nk0Qi3yEFUqHvfn/w/BifZf6bOIZ+dCinI7XIoUFemY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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