SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad759a6d6f7bb8dad5fce9e9e1b71d4c9bb49a0e982897185365c58ac5245335' 
  AND token = 's+UAlRfZJszhE2MeoQPDPiIPYwJzLgXq1BicAIhSVDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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