SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9087fcd16d14aea09a791d10f53138d0af03e4af7851c36cbb8872a4fec84bb3' 
  AND token = '5lmNNPxvweHo4ryIyRwJaHjAws+dp8Q9J3M5uenwk7Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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