SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68ae3dafd6726a01d6941d00762cc3064a83cb30f57f74c57a1cecbb4638cd8d' 
  AND token = 'r5O6WWuR9tW1wZdFLTr7WHjqDh6b4waAf1XvGJL5Spc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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