SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4cce4dae5c1f68d704740ba0229493b042414c30ab059df23de7dffceac2a0b' 
  AND token = 'xPJ9JwMbFH+a8z0dtGqixhHwUqSy6v4cVEJaxQjCt3s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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