SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3abbac0a3c5fc4b402da964ffefcf63eb310cfac39da384ca6f810f6724cbabd' 
  AND token = 'k6j/GRsQpF7QZwi9NvzzOcTxzdWduSRwHxV6Tx7pMlA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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