SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe4074390ad05eddc1024a91563f03b5a785b300a04c5c24f89a5e70bd356cba' 
  AND token = 'yYpqgBtjo3Xevjso1oI0tN0rOPL8SAULo9nS1G7Jz3c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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