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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9624016aef0d5f55dc560855ef8ebff374a33e0615e2516fe7ee57d43dc41a78' 
  AND token = 'a6NfTTPLSP5Bbz9YdKLvBEkQIhBsWAbxC76Zv1RFgbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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