SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d4c37fa44bcf1d26236831a7913c37f753944a5abdf79dfdb9cd821186cb8ad' 
  AND token = 'k2TKN4bt3vwD0VwSYaHc8dAjlvPstdFLyTuF2G8CCmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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