SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c0cc768d21574b10841ef28fb115194f490c796eb1d4e71ba68fd6f10835a219' 
  AND token = 'v5QUj0QqvXAmi9axMOkojRudjOlQJg25SURBh8dECWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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