SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7fdbcbca53d50e75aad4315ec833e3e39b7965f0d72604b0f53b867761dcafa' 
  AND token = 'MIhCXe4hELc06b9lEjSubTp+pXf+BPYanurZmBeTnWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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