SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd558097b60c7de1465ec66a447a49d291dce05b4aec0a903aba8b6ec822858b3' 
  AND token = '+G9qk2MBG7v/rDWasfwjBYlvZh1fH3NN7xLcdmILg8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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