SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6d9f744ab451c19bf4ef9870259cc45b98641ab5c7dbf7d78e620fe02ebe600' 
  AND token = 'A9iT1b7CtdelkXwL7P2R5gFTihGAFoeaROLUQ/2VwMo=' 
  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"
    }
  }
}