SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e8a78743df842d4b934980baa19280e0219beb780f2a6ff97819661f3337fbe' 
  AND token = 'g4SKDiNHBHyuFYo7kCjPDmkz7vpylOZ4vveKVKYisGc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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