SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b84e461fbb294c351d4413dd6c0a0236ce1023098f7e6ec4d21329d9aca09643' 
  AND token = 'lkqG0elXsrmNRY2FVaXdiuZ6g7oSZh1spW8Tys8wLMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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