SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ee2501e44b6e27ce746ad0a3cb50e785d9d9baf08ddbde569850cae21b594a0' 
  AND token = 'L9eht+jMrl77wfZf9veEG+SbjyxNQeZUy+CKSYO5iTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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