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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd271d14a36c78effe44462c13ba5c6a6de043fb76f5a09898aa7edfd52c69c36' 
  AND token = 'YUHL5Vb1Fiusb9KIJ8t0fsgbDKLKSZT3C5JhX6ygZ20=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}