SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'da2ea8f43313b421b30ee242a38d127ceede09974a6d20e2748138eae4c5e831' 
  AND token = 'LHUnyrR4EUJpM4haqcyoudK8FbFeeDW74wLStP8ehsY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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