SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '199c1473f8088180aad4d131c83496df1e335cec32dcf6c72095545552eb099e' 
  AND token = 'S+PjOtShEJGR3/Xdrp1PqewYBGaNayYZh+SrqUBseLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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