SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c81d19b331128b1d5fed2196725e1a337c10641105e1b3688020526968ab4ef2' 
  AND token = 'DDbtr37ZBDngCVkoqkPBdKpylprNhW5LGbIHLO4A4E0=' 
  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"
    }
  }
}