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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b402fdfe7a91ad2ac98d7ea2153bb75eb4726d43bf88a032779cc0d08ddd479b' 
  AND token = 'XRWeGIoFpZd1sC9LA+Hl1Hu3T98QoY2fe40z0BHQs6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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