SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db08cc9a6b1bc91590195affb9e23438041ea4ca905df36b32043d54675f5123' 
  AND token = 'e9GuwsAnBRs5s0tjtSd439IleRijWCt+WJ+BQJCRIWs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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