SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c528dea75ed48e6db485a08e42a6f02b7100db4b28642d472dec78448cc2b3c7' 
  AND token = 'JykSaYsmeaOtGSgsIlWxX7ZD7JcyTkn/K4j/AtoSZLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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