SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf655fbb9e2db35b6a49310fe170d802088653947fdbebf16a997aa440f2482c' 
  AND token = 'N71WfpDYARO8OqsHw+kxa1uDImvZ5PBQPT/oP4JL0zE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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