SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fc1adfc1d5f2ea43098978d895d4efa4d742299043d3fd651e2d9268cc7386f' 
  AND token = 'dXFdCvmbdaLLqluc3g+IoEWthg8XntIYNXFN3eIoB64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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