SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5f714ab32f124c48f6eaab815f65469401586a598978d3b53d7674283101318' 
  AND token = '7kCDL0AhZz63YKKtm9P/T5pcLJNTx014GCq9eLpeowc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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