SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a9466b524c4114b26d30489122d93c6beb5c3fadb7571edcdf50141706effc0' 
  AND token = 'ay3RGK1CQqmUjDBL/eAjf1EEWpcR/JmavuyRw/28vr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}