SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70be6b04f5b68024dc9898c6f662be6f2884ffdef198903eae9e5c13699721d4' 
  AND token = 'JgQQREmA7ESbXkKvwzSZLcYaPZdpQwXME03UPfnZa9s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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