SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f9e7f14251e7ed13273dfe24196147543e39a58836f96f750e806f66179117f' 
  AND token = 'ZDzU1mHYUWaqypxmVOkUHNgyuZQWbNAUSMUxB1yAX44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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