SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fab4fc832c8f76e96a600f899f509d1d8a16358aed31c8c387885120fc50624b' 
  AND token = 'NcRxZ+FB7nxJZDT4YI1iPceluWKCObP/1ZhumbzgWT0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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