SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef06c68bfcfcb743fa6a41896012ddc495a8807fee0a4f6c4c897f9a60b34703' 
  AND token = '7Xcu+qbnFYyP4jFWkT8BxKGatAxFYaj3NHW2qMHhrHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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