SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1348a117b68eb7235060d23903d2f15417d7a42a86fba412e54802838f07720f' 
  AND token = 'ROYkqhOYR0eg3oaaMqLrboIVU87mJ3UaZpNEIkww4s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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