SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6d458166714a6ac17920d2703c519ef911fb4a65c1ae389960de11af69a85bf' 
  AND token = 'P7BQsL9y2oSY8Mn2YiRdka5eE5tYTWj0yOWcD8hspJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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