SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '92b38cfb6991a28adf8025a6f68eee7b4c06e79fa0afc1e4be258a093b5129b7' 
  AND token = 'h5QoYLRJMOlw0mM7/ThvV5V+bjglGn1LplDWHanULpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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