SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e9dcbce624b012534def794d0684827e101c46edfeddce1676cd75b56b6a574' 
  AND token = '5T0Xd9NmGKnq40AuKCKZE37s7i5ciilWfm/G0Oyt9kI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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