SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51383ee918989c43abafa34f966309f75c32cc8d8e4f9d63f2aed0b940eeade7' 
  AND token = 'SCE2aDdXgfiqCNR1B93V+ydPiSvu7FW+VitNmTGjIWI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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