SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49a549938d0a05199e08eaaa7a12c5d5df52a875afb81d8e074e9c1083f65320' 
  AND token = 'RAaIiyY44wgRKCZZbueKD3YtBxjW2zpyIyRTuHp/QV8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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