SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f8be6d9ef31f662ad0f0b2b58808bd0618065d2f6bb11a7443e3c0374b1c2ef9' 
  AND token = 'DF074By7UYxkq3WDjYV1DgQr+/zMsgrzayP2XRx4/ho=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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