SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91375a89dfd77c824899457dd820ce0431226c4bdcfc8dd07e3c6e9fa45af1a5' 
  AND token = 'Qsv5YFJeLwzhwWEL3As7XZgiAJeN3JYJxR1CQG/g8r0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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